As I said, "if a lethal pandemic flu that's sensitive to tamiflu comes around....". It's well known old news that H5N1 (the asian "bird flu") isn't sensitive to tamiflu.
The side effects are significant in a small portion of the population. Most people can take it with minimal side effects. All effective drugs have side effects, and most have drug-drug interactions. If I take erythromycin, I get seriously ill. That doesn't mean erythromycin should be taken off the market. It doesn't mean that nobody should take it. That just means I shouldn't take it.
If the clinical trial you were part of was a real properly designed trial, half of you were being given pills without vitamin C in it. The person who gave you the pills didn't know the difference, and the person who was monitoring you didn't know the difference. This is called a double-blind controlled study, and is universally recognized as the only way to actually tell whether or not a treatment is effective. Many treatments (especially those that supply "common wisdom" treatments like vitamins) produce a dramatic placebo effect-- people who think they're taking Vitamin C but who are taking just lactose pills will show reduced rates of infection and will report milder symptoms. You said yourself and the rest of your company either didn't get the flu or had reduced symptoms. If this was a decently designed, placebo controlled experiment, than your observation would indicate that the results were the same for both those who actually got the vitamin pill, and for those who got the placebo. If you had noticed that half of the company didn't get sick, but the other half did, then you might have something.
I certainly wouldn't suggest that the grandparent poster should take tamiflu-- they clearly do have side effects, and anyway the current version of swine flu running around isn't doing much damage. What I took (and take) exception to the the GP credulously taking one (or for that matter, many) doctor's anecdotal experience as being conclusive, and then credulously accepting an unproven folk remedy as a treatment.